There exists much effort in addressing the basic need for an efficient power source. One such effort is a hybrid drive system including an electric motor in driving relationship with at least one driven wheel, a fuel powered heat engine, and a clutch to engage and disengage the engine to the driven wheel. The clutch may be disposed between the engine and the electric motor. To provide a shock free engagement of the engine to the driven wheel in all travel situations would require operating the engine and the electric motor in cooperation with operation of the clutch after a command to engage the clutch.